That's not a squeal, it's you playing in the upper octave! most easily accessible via a 'leak' [as you seem to have discovered]. Check out Callum Armstrong's Youtube videos or the competition sound files on this site to see how this 'squeal' can be exploited with dramatic effects!

I'll be honest and say I don't like all those forced extra notes. The base chanter sound is awful as a result in my opinion, far too nasal and weak to my ears. There's room for extra capability on a well crafted and played chanter no doubt but in my opinion stick with the tried and tested and get that sorted before getting adventurous especially when still getting to grips with basic technique.